Answer:
The splitting is going to be larger for CO.
Step-by-step explanation:
"The ligand field splitting in a coordination complex is determined by the strength of the interaction between the metal center and the ligands, which is affected by various factors, including the ligands' identity. CO ligands are stronger field ligands than H2O ligands, meaning that they interact more strongly with the metal center and cause a larger ligand field splitting. Therefore, if H2O ligands are replaced with CO ligands in this experiment, we would expect the ligand field splitting to be larger for CO."